Trimethylamine Complexes of Alane as Precursors for the Low-Pressure Chemical Vapor Deposition of Aluminum

Aluminum films were deposited in a hot-wall, low-pressure chemical vapor deposition reactor at temperatures as low as 100 °C by using (Me₃N)₂AlH₃. Typical growth conditions were 180 °C substrate temperature and 25 °C for the precursor temperature. No carrier gas was used in any of the depositions, and the deposition rate on Si(100) under the above conditions was 0.9 μm/min. Changing the substrate temperature to 280 °C resulted in an increase in the deposition rate to 3 μm/min. Substrate materials included glass, polyimide films, and Si wafers. The surface morphology of the films was rough under most conditions. Pretreating the surface with TiCl₄ allowed smoother films to be deposited at lower temperatures. At 100 °C mirrorlike films were grown that exhibited a high degree of crystallite orientation. The (111) layers were found parallel to the surface. Resistivities of the as-deposited films ranged from 2.8 to 4.5 μΩ cm. A discussion of the deposition chemistry and a comparison to depositions using triisobutylaluminum are presented.